#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<assert.h>
char* my_strncat(char* dest,const char* src,size_t num)
{
    char* ret = dest;
	assert(dest != NULL);
	assert(src != NULL);
	while(*dest != '\0')
	{
	    dest++;
	}
	while(*dest++ = *src++)
	{
	    ;
	}
	return ret;
}
int main()
{
	char arr1[20] = "abcdef"; 
	char arr2[] = "xxxxx";
	printf("%s\n",my_strncat(arr1,arr2,4));
    return 0;
}